Mythbusters bust Fingerprint Security

In relation to: Fingerprint authentication & RFID Implants

When reading up on BennyK’s blog I noticed the article he spotted at KWC. It’s a transcript about Episode 59 of Mythbusters (August 2006).

Cheap biometric thumb scanner for computers

They felt that a cheap fingerprint scanner for computers would be an easier target than the door lock, so they could test some of their ideas on it first. They used the APC Biometric Password Manager, which retails for about $50.

Their main challenge was getting a good print. They first tried using forensic dust on a fingerprint that Jamie left on a piece of glass. They result wasn’t very photographable, so they then decided to stick the print and superglue in a vacuum chamber. Much like an episode of CSI, the superglue fumes adhered to the fingerprint and they were able to get a much better print when they dusted it.

Now that they had the fingerprint, they had to create a print of it that they could defeat the computer scanner with. They tried three different versions:

  • Paper print of Jamie’s fingerprint: They made a photocopy of the print and placed it on the scanner, but the print was too ‘muddy’. access denied
  • Ballistics gel print of Jamie’s finger: This was a many step process in order to create a ballistics gel print off of a etched copper board. They first printed out Jamie’s print onto acetate. Then they created a raised version of the print using a copper-coated circuit board. The circuit board is coated with a photo-reactive material, and by laying the acetate print on top and exposing it to light, they were able to leave a copy of the print on top. Then they immersed the board in acid in order to etch away the copper, leaving a raised print. Finally, they made a cast on top using ballistics gel. access denied. The print still wasn’t clear enough for the computer as the edges weren’t defined enough.
  • Ballistics gel print II (cleaned up): Jamie had the idea of enlarging the fingerprints, tracing over them in sharpie to clean up the jagged portions of the print, and then creating the ballistics gel print. access granted

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